Just installed VNC at home. Running the Windows server on our XPHome machine, and the client on my laptop - dual booting Win2K and Linux.
My laptop resolution is smaller than the desktop, so I wanted to get VNC to scrolling full-screen (displays 1024 of the 1280 at a time; when you nudge the edge with the mouse it scrolls to display the rest). But just:
didn't do everything I wanted - scrolling wasn't perfect, and it couldn't interact properly with KDE, so I wanted it separate.
Did some hunting in the X11 documentation, eventually cracked it. Only takes one line, so you can do it as a shell script or just a shortcut from the desktop:
xinit /usr/bin/vncviewer -fullscreen -- /usr/X11R6/bin/X :1
The ':1' bit specifies display number 1 (F8 key) (KDE is running on :0, F7). If you're running any other X servers you could make it :2 instead. I think my machine allows about 4 instances of X, but I haven't tested it all the way.